http://hdl.handle.net/1834/1355 Thu, 16 May 2013 18:55:17 GMT 2013-05-16T18:55:17Z http://http://www.oceandocs.org:80/retrieve/4181/INIDEP.jpg http://hdl.handle.net/1834/1355 http://hdl.handle.net/1834/4222 Title: Larval and juvenile growth of two Patagonian small pelagic fishes: Engraulis anchoita and Sprattus fuegensis Authors: Brown, D.R.; Sánchez, R.P. Abstract: Patagonian anchovy (Engraulis anchoita) and sprat (Sprattus fuegensis) constitute the two most important pelagic resources of the Argentine Patagonian shelf (SW Atlantic). Age and growth parameters of larvae and juveniles of both species were determined analyzing otoliths daily increments. A total of 404 anchovies (4.1-33 mm SL) and 157 sprats (5-41 mm SL) were analyzed. The Laird-Gompertz growth model was fitted to the length-at-age data of anchovies: L(t) = 4.2 exp (2.28 (1-(-0.034 t))). The parameters of the model were: L: 41.06 mm; the inflection point: 15.11 mm and 27 days; and the maximum growth rate: 0.51 mm day-1. The length-at-age data of sprat larvae and juveniles were represented in two linear models: L(t) = 0.32 t + 7.6; and L(t) = 0.22 t + 6.6. Slopes represented mean growth rates, 0.32 and 0.22 mm day-1 for larvae and juveniles, respectively. Variations in length-at-age between years were determined through the analysis of individual growth trajectories. Variations were found in sprats, not in anchovies.; La anchoíta patagónica (Engraulis anchoita) y la sardina fueguina (Sprattus fuegensis) constituyen los dos recursos pelágicos más importantes de la Plataforma Patagónica Argentina (Atlántico SO). Se determinaron la edad y el crecimiento de larvas y juveniles de ambas especies mediante el análisis de incrementos diarios de los otolitos. Se analizaron un total de 404 anchoítas (4,1-33 mm LS) y 157 sardinas (5-41 mm LS). Se ajustó el modelo de crecimiento de Laird-Gompertz a los datos longitud-edad de las anchoítas: L(t) = 4,2 exp (2,28 (1-(-0,034 t))). Según el modelo: L~!: 41,06 mm; el punto de inflexión: 15,11 mm y 27 días; y la máxima tasa de crecimiento: 0,51 mm día-1. Los datos longitud-edad de larvas y juveniles de sardina fueguina se representaron en dos modelos lineales: L(t) = 0,32 t + 7,6 y L (t) = 0,22 t + 6,6. Las pendientes representaron las tasas de crecimiento medias, 0,32 y 0,22 mm día-1 en larvas y juveniles, respectivamente. Las variaciones en longitud-edad entre años se estudiaron mediante el análisis de trayectorias individuales de crecimiento. Se encontraron variaciones en las sardinas fueguinas, no en las anchoítas. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/1834/4222 2010-01-01T00:00:00Z http://hdl.handle.net/1834/4223 Title: Estimación de la edad y el crecimiento de la merluza austral Merluccius australis (Hutton, 1872) del Mar Argentino Authors: Gorini, F.L.; Abachian, V.E.; Giussi, A.R. Abstract: Southern hake (Merluccius australis) age and growth were estimated using sagittae otoliths obtained in research cruises and observers programs in the Argentine Sea (SW Atlantic). The only annual growth ring observed, formed by two bands, one hyaline and another opaque, corresponded to winter and summer growth, respectively. According to the analysis of otoliths edge, birthday was established on 1st July. Within the age range observed, that comprised 3-18 year old specimens, age groups 7, 8 and 9 were the most frequently identified in both sexes. Growth parameters estimates showed significant differences between them.; Se presenta un análisis del crecimiento y una estimación de la edad de la merluza austral (Merluccius australis) del Mar Argentino (Atlántico SO) realizados utilizando otolitos sagittae provenientes de campañas de investigación y del muestreo realizado por observadores. El único anillo de crecimiento anual que se observó, formado por dos bandas, una hialina y otra opaca, correspondió al crecimiento de invierno y verano, respectivamente. De acuerdo con el análisis de borde, la fecha de cumpleaños se fijó el 1º de julio. Dentro del rango de edad observado, que abarcó especímenes de entre 3 y 18 años, las edades 7, 8 y 9 fueron las que se identificaron con mayor frecuencia en ambos sexos. La estimación de los parámetros de crecimiento permitió observar diferencias significativas entre ellos. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/1834/4223 2010-01-01T00:00:00Z http://hdl.handle.net/1834/4224 Title: Alimentación del calamar Illex argentinus en la región patagónica durante el verano de los años 2006, 2007 y 2008 Authors: Ivanovic, M.L. Abstract: The information gathered during four research cruises carried out in January and February of 2006, 2007 and 2008 allowed to analyze the summer feeding pattern of Illex argentinus squid in the shelf and slope of the Patagonian region (43º S-51º S), SW Atlantic Ocean. Intake, that took place during daytime, had its peak as of midday. Of the preys eaten amphipods and euphausiids, two groups of zooplanktonic organisms, represented 71-99% of the diet. The most frequent preys found in three of the four cruises corresponded to amphipods, represented by a single species, the hyperiid Themisto gaudichaudii, that accounted for over 50% of the food consumed. When depth of the catching area was beyond 100 m an increase in consumption of squid and fish by specimens above 20 cm ML was observed. No clear trends were found between the type of prey consumed and the time of catches or the degree of stomach repletion of the predator. The diet, of low diversity, showed that 56-62% of the squids studied fed on a single type of prey.; Sobre la base de información recopilada durante cuatro campañas de investigación que se realizaron en enero y febrero de 2006, 2007 y 2008 se analizó el patrón de alimentación de verano del calamar Illex argentinus en la región de la plataforma y el talud patagónicos (43º S-51º S) del Atlántico SO. La ingesta, que tuvo lugar durante el día, mostró su pico de intensidad a partir del mediodía. Anfípodos y eufáusidos, dos grupos de organismos zooplanctónicos, representaron el 71-99% de la dieta. Las presas más frecuentes en tres de las cuatro campañas fueron los anfípodos, representados por una única especie, el hipérido Themisto gaudichaudii, que constituyó más del 50% del alimento ingerido. Cuando la profundidad del área de captura superó los 100 m se observó un aumento del consumo de calamares y peces en ejemplares de tallas superiores a los 20 cm LM. No se detectaron tendencias definidas entre el tipo de alimento consumido y la hora de captura o el grado de repleción estomacal del predador. La dieta, de baja diversidad, mostró que el 56-62% de los calamares estudiados ingirió un único tipo de presa. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/1834/4224 2010-01-01T00:00:00Z http://hdl.handle.net/1834/4219 Title: Precisión en las evaluaciones por área barrida de algunos peces demersales costeros entre los 34º S Y 42º S, Atlántico Sudoccidental Authors: Hansen, J.E.; Hozbor, N.; Lagos, N.; Martos, P. Abstract: To estimate the biomass of six species, the stratified design used at present for demersal coastal fish stocks is compared against other design alternatives. Density data (t mn-2 between 34ºS and 42ºS, from the coast line to 50m depth, corresponding to whitemouth croaker (Micropogonias furnieri), patagonian smoothhound (Mustelus schmitti), stripped) weakfish (Cynoscion guatucupa), angular angel shark (Squatina guggenheim), brazilian flathead (Percophis brasiliensis) and skate (Sympterygia bonapartii) collected in surveys carried out in spring and winter in the Argentine Sea (SW Atlantic), were analyzed. The spatial distribution of the species was strongly contagious and influenced by bottom salinity. Different marine zones that showed special salinity features for a long time were defined to test bounded strata accordingly. The simple random design caused, in general, greater uncertainty than any of the stratified designs when using the 17 fixed strata surveyed during the last cruises or when two ‘new designs’ that included 7 strata, different for spring and winter, were adopted. Although no stratified scheme showed superiority to assess all and every species, their comparative advantages are discussed. Assessments made with the design used at present seem to be less efficient in winter thus suggesting that, in the future, surveys should be carried out in spring. No great differences among designs were found when the efficiency gain-sample size relation was studied and that resulted very low above 150 trawls if compared to the cost of using the research vessel. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/1834/4219 2010-01-01T00:00:00Z